|||||||||||||||| USOO5147908A United States Patent (19) 11 Patent Number: 5,147,908 Floyd et al. 45) Date of Patent: Sep. 15, 1992

(54) CATIONICPOLYVINYL ALCOHOL BINDER 4,405,375 9/1983 Gibson et al...... 106/277 ADDITIVE 4,461,858 7/1984 Adelmann ...... 524/503 4,528,316 7/1985 Soerens ...... 524/503 75) Inventors: William C. Floyd, Chester; Louis R. 4,537,807 8/1985 Chan et al...... 428/74 Dragner, Rock Hill, both of S.C. 4,816,540 3/1989 Onishi ...... 527/300 4,837,087 6/1989 Floyd et al...... 428/51 73 Assignee: Sequa Chemicals Inc., Chester, S.C. 4,888,386 12/1989 Huang et al...... 524/503 X (21) Appl. No.: 587,012 4,954,577 9/1990 Dinwald et al...... 524/503 X 22 Filed: Sep. 24, 1990 OTHER PUBLICATIONS 51) Int. Cl...... CO8L 3/04 Zunker, David W.; "Incorporating The Benefits Of 52 U.S. Cl...... 524/49; 524/55; Polyvinyl Alcohol At the Wet-End Of Papermaking'; 524/503; 525/57; 525/58 1982 Papermakers Conference. 58 Field of Search ...... 524/503, 49, 55, 57, 524/58 Primary Examiner-Joseph L. Schofer Assistant Examiner-J. M. Reddick 56) References Cited Attorney, Agent, or Firm-Mitchell D. Bittman U.S. PATENT DOCUMENTS 57 ABSTRACT 3,573,236 3/1971 Barlow ...... r 260/7 3,597,313 8/1971 Williams et al...... 162/67 A cationic polyvinyl alcohol binder additive is prepared 3,600,342 8/97 Nickerson et al...... 260/17 suitable for addition in the wet-end of a paper making 3,700,61 0/1972 Nickerson et al...... 260/17 R process by reacting a blocked glyoxal resin, a cationic 3,810,783 5/1974 Bomball ...... 117/122 S -soluble reactive polymer and a polyvi 3,912,529 10/1975 Kotani et al. ... 106/87 3,932,335 l/1976 Gorton ...... 260/29.6 nyl alcohol polymer. 4,169,088 9/1979 Hansen ...... 260/29.6 4,311,804 1/1982 Raghava et al...... 524/503 24 Claims, No Drawings 5,147,908 1. 2 No. 4,461,858 is that the solutions are stable only at very CATIONIC POLY WINYL ALCOHOL BINDER dilute concentrations (e.g., 3%) and gel at higher solids ADDITIVE (e.g., gel in minutes at 12% solids). Another drawback of U.S. Pat. No. 4,461,858 is that in forming the MF BACKGROUND OF THE INVENTION 5 resin acid colloid at a pH near 1 to 2 concentrated hy This invention relates to preparing a cationic polyvi drochloric acid is used, which is a very corrosive solu nyl alcohol additive suitable for addition in the wet-end tion which requires exotic materials for proper han of a paper making process and more specifically to a dling. non- additive which is a stable fluid aque A further problem of the prior art is that the amount ous solution at high solids yet imparts improved perfor O of cationic charge imparted to the polyvinyl alcohol is mance to the resultant paper. difficult to control as the melanine-formaldehyde resin There are numerous commercial wet end additives acid colloid is a variable composition. In addition, the being used in paper making. Among the additives are use of melanine-formaldehyde resins or polyamino cationic starches and melamine-formaldehyde resins. polyamide epichlorohydrin adduct as a wet-end addi Cationic starches are used for improving retention of tive makes the resultant paper difficult to repulp and cellulosic fines, filler and pigment, and also for increas recycle because the resin does not readily break down ing the dry strength of the resulting paper. However, during repulping. the use of cationic starch can lead to irregularities in performance (irreproducibility of batches, low solution SUMMARY OF THE INVENTION stability, low wet strength), incompatibility with other 20 Briefly, the present invention prepares a stable aque components in the furnish (alum, size, other salts), and ous non-formaldehyde based cationic polyvinyl alcohol high biological demand (BOD) for additive not binder additive by reacting an aqueous solution of on the pulp or recycled, and which is lost in the waste Water. blocked glyoxal resin with a cationic water-soluble, Other wet-end additives are often used to confer 25 aldehyde-reactive polymer and a polyvinyl alcohol permanent wet strength to the resulting paper, such as polymer. Stable fluid solutions of the additive can be cationic urea-formaldehyde UF resins, amine-contain obtained at up to 12% or higher solids levels. ing polyamides treated with epoxides (e.g. Hercules DETAILED DESCRIPTION OF THE "Kymene' 557) or melanine-formaldehyde (MF) resins INVENTION (e.g., "Parez' 607 of American Cyanamid). However, 30 UF resins are slow curing on the machine, while the The present invention prepares an additive which is polyamides are relatively expensive, slow to absorb on highly adsorbent on cellulose pulp and as such is suit the cellulose pulp, and make repulping of the paper able for incorporation in the wet-end of the paper mak relatively difficult. The MF resins show poor pigment ing process. Significantly improved properties in the and filler retention, and also exhibit low water absor 35 paper were exhibited including internal bond strength, bency, whereas absorbency is often desired along with dry tensile strength, reduced elongation and sizing ef wet strength. All of these types of additives give only fectiveness. In addition, because this additive can utilize modest enhancement of dry strength. Also, none of the precisely defined polymers of known cationic charges, above types are now recognized as improvers of wet the amount of cationic charge imparted to the polyvinyl web strength (at their usual concentration of applica alcohol can be precisely controlled, thus enabling in tion) which would permit greater production control proved control over the drainage and retention proper and in some cases, increased productivity. ties of the paper and avoiding the problems due to ex Polyvinyl alcohol has been used for surface sizing cessive cationic charge, such as flocculation of the fi and surface coating because of its excellent film forming bers. Further, since the glyoxal resin component uti and binder characteristics. However, polyvinyl alcohol 45 lized in the additive is destroyed at higher pH's (e.g. is not added directly to the wet-end of the paper making above pH 10), the resultant paper can be more readily process because most of the polyvinyl alcohol would repulped and recycled by utilizing higher pH's during pass through the wet paper web end into the white repulping. water. The absorption and retention of unmodified alco The additive of the present invention is a reaction hol on fiber and filler is insufficient to resist the volumi 50 form of a blocked glyoxal resin, a cationic water-solu nous water discharge and the hydrodynamic forces ble, aldehyde-reactive polymer and a polyvinyl alcohol present during paper formation. polymer. This additive is stable in solution at solids Methods have been disclosed for associating polyvi levels even as high as 12% by weight solids or higher. nyl alcohol with a positive charge to allow it to be The glyoxal resin component of this mixture is incorporated into the wet-end of paper making by react 55 blocked to inhibit it from reacting fully with the other ing the polyvinyl alcohol with trimethylolmelamine components prior to drying. Inhibiting the reactivity of acid colloid (see Tappi Journal, Volume 66, No. 11, the glyoxal resin allows a product to be formulated at 11/1983). Also U.S. Pat. No. 4,461,858 discloses a higher solids and/or lower viscosity than otherwise polyvinylalcohol/melamine-formaldehyde resin inter possible with unblocked glyoxal resin. The blocked action product. However a serious drawback in the use glyoxal resin reacts with both the polyvinyl alcohol and of such materials is that they contain free formaldehyde. the cationic water-soluble, aldehyde-reactive polymer, The presence of free formaldehyde is undesirable, not loosely attaching them together thus imparting a cati only because of its unpleasant odor, but because it is an onic charge to the polyvinyl alcohol. The blocked gly allergen and an irritant, which can cause severe reac oxal resin appears to crosslink by a two-step process tions in the operators who manufacture the agent and 65 with the first step occurring in the reaction in aqueous who treat and handle products containing it. A further solution with the cationic polymer and polyvinyl alco drawback for the cationic polyvinyl alcohol/melanine hol, with the second crosslinking reaction being de formaldehyde resin products as disclosed in U.S. Pat. layed until the paper is dried. Using this invention, it is 5,147,908 3 4. possible to prepare a paper additive with a high level of group having 1 to 4 atoms and X may be C,O, or solids. With free (unblocked) glyoxal, the additive can N; when X is O.R3 and R4 are each zero; when X is N, be unstable resulting in thickening or gelling of the R3 or R4 is zero. additive, or the additive may show unacceptably high Typical examples of such urea reactant compounds viscosity or gelling over time. include, but are not limited to ethylene urea, propylene Glyoxal readily reacts with binders such as polyvinyl urea, uron, tetrohydro-5(2 hydroxyethyl)-1,3,5-triazin alcohol and with the cationic water-soluble, aldehyde 2-one, 4,5-dihydroxy-2-imidazolidinone, 4,5-dimethoxy reactive polymer and other polymeric agents in a cross 2-imidazolidinone, 4-methyl ethylene urea, 4-ethyl eth linking reaction. Crosslinking causes the mixture of ylene urea, 4-hydroxyethyl ethylene urea, 4,5-dimethyl glyoxal resin and the polyvinyl alcohol and/or poly 10 ethylene urea, 4-hydroxy-5-methyl propylene urea, 4 meric agents to thicken or gel. By suitably blocking the methoxy-5-methyl propylene urea, 4-hydroxy-5,5 di glyoxal resin, the reactivity can be controlled so that methyl propylene urea, 4-methoxy-5,5-dimethyl propy final crosslinking occurs in the paper as it is being dried lene urea, tetrahydro-5-(ethyl)-1,3,5-triazin-2-one, tet and cured. Furthermore, judicious choice of levels of rahydro-5-(propyl)-1,3,5-triazin-2-one, tetrahydro-5- the various components allows the papers properties to 15 be enhanced upon drying the paper with the glyoxal (butyl)-1,3,5-triazin-2-one, 4-hydroxy-5,5-dimethyl resin reacting with the polyvinyl alcohol, the cationic pyrimid-2-one, and the like, and mixtures thereof Gen polymer and the cellulose pulp. Generally, the amount erally, the level of glyoxal to urea is within the range of of blocked glyoxal resin is within the ratio of 1:4 to 25:1 about 0:8 to 2.2:1. Included within the blocked glyoxal by dry weight of the blocked glyoxal resin to cationic 20 resins are those prepared as described in U.S. Pat. Nos. polymer, preferably about 1:1 when the cationic poly 4284758, 4345063, 4455416, 4547580 and 4625029. mer is an acrylamide and about 1:2 when the cationic The polyvinyl alcohol polymer component of the polymer is a starch. Both the glyoxal resin and the cati product of the present invention can be a "completely" onic polymer generally comprise 10-60%, preferably hydrolyzed grade (mole percent hydrolysis of 25-40% by dry weight of the additive. Mixing polyvi 25 groups 99.0 to about 100%), a partially hydrolyzed nyl alcohol or a cationic polymer with free (unblocked) grade (percent hydrolysis 80-90%), a polymer of inter glyoxal, or adding free glyoxal to an additive containing mediate level of hydrolysis, or blends thereof. The com such polymeric agents generally causes thickening or pletely hydrolyzed grades and also the higher molecu gelling due to premature reaction. lar weight commercial grades are preferred when pa The glyoxal may be blocked by reaction with a block 30 pers are desired with the highest wet strength proper ing component becoming a blocked glyoxal resin. Suit ties. The polyvinyl alcohol should have a degree of able blocking components include urea, substituted polymerization of from about 600 to 3000, as reflected ureas (such as dimethyl urea), various cyclic ureas such in the inherent viscosity values Tinh) of from about 0.3 as ethylene urea, substituted ethylene ureas (such as to about 1.4 dl/g. The inherent viscosity is measured in 4,5-dihydroxyethylene urea), propylene urea, substi 35 water a 30' C., at a concentration of 0.5 g/dl. This tuted propylene ureas (such as 4-hydroxy-5-methyl-pro approximately corresponds for many commercial pylene urea, or 4-hydroxy-5,5-dimethyl propylene grades of polyvinyl alcohol to a solution viscosity (4% urea), glycols (such as ethylene glycol to make 2,3-dihy aqueous at 20' C., Hoeppler falling ball method), of droxydioxane, or dipropylene glycol to make an oligo from about 4 to about 160 cps, with about 10-70 cen meric condensation product), polyols (i.e. containing at tiposies being preferred. Generally the polyvinyl alco least three hydroxy groups such as sorbitol or such as hol is added at a level of 40 to 90%, preferably 60 to glycerin to make 2,3-dihydroxyl-5-hydroxymethyl di 75% by dry weight of the additive. oxane) as well as unalkylated or partially alkylated The polyvinyl alcohol component of the present polymeric glyoxal derived glycols, such as poly(N-1',2'- invention can also be a copolymer of , such dihydroxyethyl-ethylene urea). Preferably, the block 45 as one obtained by hydrolyzing a copolymer of vinyl ing component is a urea or cyclic urea because the acetate with small amounts (up to about 15 mole per blocked glyoxal resins formed are very stable providing cent) of other monomers. Suitable comonomers are e.g. a long shelf life. esters of acrylic acid, methacrylic acid, maleic or fu The reaction of the glyoxal and the blocking compo maric acids, itaconic acid, etc. Also, copolymerization nent, preferably a urea or cyclic urea, generally takes 50 of with hydrocarbons, e.g. a-olefins such place within the temperature range of about 25' to 100' as ethylene, propylene or octadecene, etc., with higher C., and preferably about 40' to 80 C. In general the pH vinyl esters such as vinyl butyrate, 2-ethyl hexoate, of the reactants and resultant binder additive is about stearate, trimethyl acetate, or homologues thereof 2.5 to 8.0 and preferably is about 4 to 7.5. ("VV-10' type of vinyl esters sold by Shell Chem. Co.), The urea reactant may be urea, monourein or the like. 55 etc. gives copolymers that can be hydrolyzed to suitable If a cyclic urea is selected it may have one of the follow polyvinyl alcohol copolymers. Other suitable comono ing general formulas: mers are N-substituted acrylamide, unsubstituted acryl amide, vinyl fluoride, allyl acetate, allyl alcohol, etc. O OI Also the free unsaturated acids such as acrylic acid, C methacrylic acid, monomethyl maleate, etc. can act as COOOCS. Hy Sh H1 Sh The cationic water-soluble, aldehyde reactive poly R2RC CR3R4 R2R1C CR5R6 mer is added to the additive to impart a cationic charge. YRR1 A preferred cationic polymer is a cationic acrylamide 65 copolymer because of the ability to accurately control wherein R1,R2, R3, R4, R5 and R6 may be the same or the cationic charge. The acrylamide copolymer can be different and each may be H, OH, COOH, R, OR, or rendered cationic by means of a Mannich Reaction COOR wherein R is an alkyl or a substituted alkyl which reacts formaldehyde and dimethyl amine with 5,147,908 5 6 the amide groups of the polymer, or by incorporation of sulfite, semi-chemical, groundwood or blends of these a cationic monomer during the polymerization reaction. fibers. In addition, fibers or viscose rayon, glass, regen The cationic acrylamide copolymer is a copolymer of erated cellulose, polyamide, polyester of polyvinyl al acrylanides such as acrylamide, methacrylamide, N,N- cohol can also be used in conjunction with the cellulose dinnethyl acrylamide and N-methylol acrylamide, with pulp. The preferred pH range of the pulp stock contain cationic ethylenically unsaturated monomers such as ing the additive inter-reaction product is from about 4 quaternary salts of dimethyl amino propyl methacry to about 8; with good adsorption and filler retention late, dimethyl aminopropyl methacrylamide, methyl demonstrated over this range. The best wet strength chloride quaternary salt of dimethyl amino ethylmetha properties of the resulting paper occur in the pH range crylate and methyl sulfate quaternary salt of dimethyl 10 of from about 5 to 7.5. amino propyl methacrylamide. The cationic acrylamide Materials which could be added to the pulp slurry copolymer can also be copolymerized with additional along with additive include cationic surfactants, starch, monomers, preferably water-soluble monomers such as polymers derived from polyamides containing amino hydroxy ethyl acrylate, vinyl pyrolidone and acrylic groups along the polymer backbone, and reacted with acid, but can also be copolymerized with limited 15 epichlorohydrin (such as "Kymene" 557 from Hercu amounts (typically less than 15%) of water insoluble les). Anionic polyacrylamide polymers, fortified rosin monomer such as vinyl acetate, methyl acrylate and size, fillers, pigments, alum, etc., also can be present. ethyl acrylate provided the resultant copolymer is The sheet is then formed, pressed and dried by con water-soluble. Other cationic water-soluble, aldehyde ventional means. The latter step serves to cure the addi reactive polymers suitable for use in this invention in 20 tive and complete the crosslinking of the blocked gly clude cationic guar gum and various cationic starches, oxal resin. especially those that have been additionally modified by The amount of additive added to the pulp slurry acid hydrolysis or enzyme conversion. Cationic starch ranges from about 0.02 to about 10%, based on the dry propionamide derivatives such as those described in weight of the pulp. The preferred range is from about U.S. Pat. No, 3,740,391 are also suitable. Depending on 25 0.05% to about 3%, and will depend on the characteris the wet end chemistry of the paper machine, it may be tics desired in the finished paper product, the type of desirable to precisely control the amount of cationic pulp, and the specific operating conditions. polymer introduced in preparing the paper, since too The following examples serve to illustrate the present much charge could upset the charge balance and cause invention. All parts and percentages and proportions flocculation of the fibers and lead to poor sheet forma 30 tion, while too little charge could result in an inade are by weight unless otherwise indicated. quate amount of polymer being retained to impart desir EXAMPLE I able properties. Through the additive of this invention A series of samples was prepared at 12% total solids improved control over the amount of cationic charge is containing either 12% polyvinyl alcohol (PVOH) or obtained. 35 8% PVOH and 4% cationic polymer and resin. The To prepare the additive of this invention the blocked PVOH used was Elvanol((8)71-30, a completely hy glyoxal resin, cationic polymer and polyvinyl alcohol drolyzed medium molecular weight grade of polymer polymer are mixed in aqueous solution then heated to available from DuPont. The cationic acrylamide poly both dissolve the polyvinyl alcohol and react the com mer was a 10 mole% cationic copolymer of acrylamide ponents. Generally the components are heated to 85 to with methyl chloride quaternary salt of dimethylamino 95 C. for 10-30 minutes. Generally, stable flowable ethyl methacrylate (Sequex((8)PC, from Sequa Chemi solutions can be maintained at solids levels up to 12% cals Inc.) which exhibited a viscosity of 1340 cps (ambi and higher, preferably 5 to 12% by weight. By flowable ent temperature, Brookfield, #3 spindle, 50 rpm) at 18% is meant having a viscosity of below 3000 cps as mea solids. The resin was a the blocked glyoxal resin, Se sured with Brookfield Viscometer with a #3 spindle at 45 20 rpm at room temperature. quex((BR)R, a 1:2 cyclic urea:glyoxal condensation prod In an alternative embodiment, when a dry free flow uct at 46% solids from Sequa Chemicals, Inc. ing granular additive is desired, then such dry additive A typical procedure is described as follows: can be prepared by drying each of the components (e.g. Deionized water was charged to a 1 liter, 4-necked oven drying, freeze drying or spray drying), granulat 50 flask equipped with a mechanical stirrer, thermometer ing and mixing the components together. This dry mix and condenser. Cationic polymer and resin (if used) ture would then be mixed in aqueous solution and re were then added and stirred. With continued stirring, acted as above when desired. the PVOH was slowly added through a powder funnel The additive thus prepared can be employed using to form a well-dispersed slurry. This was heated to the conventional methods of preparing paper sheets and 55 85-95 C. for 15 minutes, then cooled. Unless gellation other cellulosic products. Preferably, interaction with occurred, this resulted in complete dissolving of the cellulose pulp material is carried out by internal addi PVOH. Viscosity was measured with a Brookfield Vis tion to the cellulose pulp prior to formation of the paper cometer, #3 spindle, 50 rpm at ambient temperature. sheet. Thus the aqueous solution of the interaction The following formulations (in grams) were prepared in product may be added to the aqueous suspension of the this manner with these results obtained: paper stock while the latter is in the head box of the Fourdrinier, at the fan pump, in the stock chest, the Itern A B C D E hydropulper or any other point in the process prior to Water 440 398.9 382.2 365.6 415.6 the point of sheet formation. The high adsorption rate Cyclic Urea/glyoxal ----- 33.3 22.2 1.1 44.4 of the additive with the pulp permits many options in 65 resin Acrylamide copolymer - 27.8 55.5 83.3 - this regard. Among the variety of pulps which may be Polyvinyl alcohol 60 40 40 40 40 effectively treated are bleached and unbleached sulfate Resin/copolymer ratio - 2:1 :1 :2 :0 (raft), bleached and unbleached sulfite, soda, neutral Viscosity, cps 2325 i440 1930 2650 788 5,147,908 8 -continued pressed between rollers and dried in a Noble Wood Model Dryer. Six sheets were formed from each experi tem A B C D E mental sample with results compiled from the three Total Solids 2%. 12%. 12%. 2%. 12% nearest in weight. The experimental products were added at a rate of 1.8g (at 12% solids) to 1440 g of pulp slurry to attain a level of 0.6%. The resin used was EXAMPLE II Sequex R, a blocked glyoxal resin from Sequa Chemi For purposes of comparison, samples were prepared cals having a cyclic urea/glyoxal ratio of 1:2. The poly and measured as in Example I with the blocked glyoxal mer used was a 10 mole % cationic polyacrylamide (a resin (Sequex(B) replaced by an experimental blocked 10 copolymer of acrylamide and methyl chloride quater glyoxal resin (a 2:1 glyoxal: sorbitol condensation prod nary salt of dimethyl aminoethyl methacrylate). The uct at 70% solids described in U.S. Pat. Nos. 4656296, PVOH was Elvanol 71-30 from DuPont. 4547580 and 4537634), glyoxal and a methylated mela The experimentals were as follows: mine-formaldehyde resin (Sunrez(B)106, 76% solids from Sequa Chemicals, Inc.). These samples were pre 15 Control-no additives pared by procedures identical to those in Example I at A-8% PVOH, 4% resin and polymer in a 2:1 dry 12% total solids. The following formulations (in grams)" ratio were used with these results obtained. B-8% PVOH, 4% resin and polymer in a 1:1 dry ratio 20 ten A B C d C-8% PVOH, 4% resin and polymer in a 1:2 dry ratio Water 43.4 39.4 410 433 40% Glyoxal - - 50 D-12% PVOH, no resin, no polymer Melanine-formaldehyde - 13.1 - 26.3 E-8% PVOH, 4% resin, no polymer resin F-8% PVOH, 4% sorbital:glyoxal (1:2) condensa Sorbitol/glyoxal 28.6 - - 25 resin tion product, no polymer Acrylamide Copolymer - 55.5 - - The hand sheets were cut into 1 x 3 inch strips for (SEQUEX PC) tensile testing on an Instron Model 1100 tensile tester. Polyvinyl alcohol 40 40 40 40 Results are as follows: (ELVANOL 71-30) Viscosity, cps 590 gelled at gelled upon gelled at 30 88 C. cooling 74 C. Dry Dry Wet Wet Tensile Tensile Tensile Tensile These results show that blocked glyoxal resins are Sample Load, Kg Strain, % Load, Kg Strain, % unique in that they do not cause gellation as do conven Control 14.98 6.97 0.73 3.54 A 17.13 4.13 1.77 4.62 tional crosslinking agents such as glyoxal or melamine 35 B 8.S. 4.45 1.56 4.22 formaldehyde resins, whether used with or without a C 25.33 5.59 3.22 6.49 cationic acrylamide copolymer. Preparation of the ad D 17.43 4.40 0.77 2.61 ditive with blocked glyoxal resin is also more conve E 19.73 5.04 0.66 1.88 nient in that the materials are ready for immediate use F 17.46 4.29 0.74 2.63 and do not require extended aging periods. The results show that the three samples containing EXAMPLE III the cationic polymer exhibit comparable to superior dry The samples prepared in Example I were drawn tensile, and significantly superior wet tensile. There was down to form films which were air dried. These films little difference between the samples containing only were measured for thickness, and tested for tensile 45 PVOH and the samples containing PVOH and resin strength and percent elongation with an Instron Model only. As a general trend, the greater the cationic con 100 Tensile Tester. Results are shown below: tent, the greater the tensile strength, indicating a greater quantity of strength-enhancing additives retained on the Thickness Tensile Tensile/Mil Elongation fibers. The unreactive cationic polyacrylamides alone at Sample (mils) (Kg) (Kg) (%) 50 the levels present cannot account for the strength en A 4. 6.94 1.74 279 hancements observed. B 4 . 8.89 2.22 7.13 C 4. 9,23 2.31 10.4 EXAMPLE V d 3 7.79 2.59 9.57 A high-charge cationic potato starch (Sta-lok 400, E 4. 9.68 2.42 7.97 55 A.E. Staley Co.) was slurried in water at 30% solids, and enzyme converted to a dextrose equivalent of 0.9. These results show that reacting the PVOH in this Final solids were 40% and viscosity was 90 cps (Brook manner greatly decreases the elongation of the polymer field #3, 100 rpm). A series of products was prepared and provides a significant increase in tensile strength. using PVOH (Elvanol(B)71-30), a blocked glyoxal 60 resin (Sequex(R)R) and the cationic enzyme converted EXAMPIE IV potato starch. The products were formulated to all be A pulp slurry was prepared from a 70/30 hardwood 10% total solids and prepared by similar procedures. bleach kraft/softwood bleach kraft pulp at a 2.5% con The water charge was weighed into a one liter resin sistency and a Canadian Standard Freeness (CSF) of kettle followed by the cationic starch solution and resin. 500. The pH of the slurry was adjusted to 4.5 with 65 The PVOH was then added. The reaction was stirred sulfuric acid. Hand sheets were formed from 240 g of and heated to 90' C. for 30 minutes, then cooled. No slurry to afford sheets of approximately 6 g in weight. gellation occurred and samples maintained a stable vis Sheets were formed in a Nobel and Wood sheet mold, cosity for at least one month. Biocide was added to 5,147,908 9 10 prevent spoilage. The following chart shows formula affording 10% solutions. Each beaker was heated with tions (in grams) and viscosities measured on a Brook agitation to 90° C. for 30 minutes, then cooled to ambi field viscometer, #3 spindle, 100 rpm at room tempera ent temperature. The bench-top sample produced a tle. clear, pale amber solution having a Gardner color of 2, and Brookfield viscosity of 435 cps (#3, 100 rpm). The A B C D E F oven-aged sample produced a clear, pale amber solution PVOH 45.00 40.00 33.00 40.00 40.00 40.00 having a Gardner color of 4 and a Brookfield viscosity Resin (45%) 5.60 110 18.90 7.40 14.80 - of 635 cps (#3, 100 rpm). Starch (40%) 6.25 12.50 21.25 16.70 8.30 25.00 These samples demonstrates the ability of this partic Water 443.05 436.40 426.85 435.90 436.90 435.00 10 ular blocked glyoxal resin to be air-dried, and for this Viscosity 480 cps 330 cps 190 cps 320 cps 385 cps 305 cps invention to be incorporated in pre-determined ratios into a one-package system. It further demonstrates the To illustrate the effect of the molecular weight of the shelf life of the dry package. cationic polymer, similar products were formulated A similar blocked glyoxal resin (Sunrez 700M, a cyc using a comparable amount of a cationic polyacryl 15 lic urea, glyoxal, glycol condensate) was air-dried as amide described in Example I. This cationic acrylamide described above. This product afforded a sticky syrup polymer is formulated at 18% solids and has a viscosity which was unsuitable for pulverizing or dry blending. of approximately 1200 cps. Other blocked glyoxal resins, particularly those of the glyoxal/glycol or glyoxal/polyol condensation type 20 G H I were found to afford similar syrups upon drying which PVOH 45.00 40.00 33.00 are unsuitable as is for a dry system. For this dry system Resin (45%) 5.60 11.10 18.90 the blocked glyoxal resin chosen needs to be dryable. Polymer (18%) 15.40 27.80 47.20 What is claimed is: Water 434.00 42.00 400.90 1. A cationic polyvinyl alcohol binder additive com Viscosity 515 cps 470 cps 240 cps 25 prising: reaction product of an aqueous solution of a blocked Comparison of G to A, H to B and I to C show that glyoxal resin, a cationic water-soluble aldehyde low molecular weight starches give cationic PVOH reactive polymer and a polyvinyl alcohol polymer. solutions of lower viscosity than higher molecular 30 2. Additive of claim 1 comprising: weight polyacrylamides. All products remained fluid, 10 to 60% of the blocked glyoxal resin and the cati without gellation or separation. onic water-soluble aldehyde reactive polymer, and EXAMPLE VI 40 to 90% of the polyvinyl alcohol polyner, by dry A dry one-package system was prepared as follows. weight of the additive. A portion of blocked glyoxal resin (Sequex(6)R 35 3. Additive of claim 2 wherein the dry weight ratio of from Sequa Chemical Corp.) was poured into a tray, blocked glyoxal resin to cationic polymer is within the forming a thin film over the bottom. This was allowed ratio of 1:4 to 25:1. to air-dry for three days until it became a dry, brittle 4. Additive of claim 3 wherein the blocked glyoxal film. The film was broken and removed from the tray, resin is the reaction product of a glyoxal with a blocking and pulverized in a Waring blender. A fine amber pow component selected from the group consisting of urea, der was obtained. This powder was non-hygroscopic, substituted urea, cyclic urea, propylene urea, substi did not form lumps and was free-flowing. tuted propylene urea, glycol, polyol and mixtures A portion of cationic acrylamide copolymer as de thereof. scribed in Example I (Sunrez PC) was poured into a 5. Additive of claim 4 wherein the blocking compo tray, forming a thin film, and allowed to air-dry for 45 nent is selected from the group consisting of urea o three days. It formed a clear, brittle film which was cyclic urea and the level of glyoxal: blocking compo pulverized in a blender. A white, granular powder was nent is within the range of about 0.8 to 2.2:1. obtained. 6. Additive of claim 4 wherein the cationic water-sol A pint jar was used as a mixing vessel into which 40 uble aldehyde reactive polymer is a cationic acrylamide g. of dry PVOH (Elvanol(8)71-30 from DuPont), 13.3 50 copolymer. g. of the above dried resin, and 6.7 g of the above dried 7. Additive of claim 6 wherein the cationic acrylan cationic acrylamide copolymer were placed. The con ide copolymer is a copolymer of an acrylamide selected ponents were in the proportions of 66.7% PVOH, from the group consisting of acrylamide, methacrylam 22.2% blocked glyoxal resin and 11.1% cationic co ide, N,N-dimethyl acrylamide and N-methylol acrylam polymer. The jar was shaken and tumbled to thor 55 ide with a cationic ethylenically unsaturated monomer. oughly mix the contents, affording an off-white pow 8. Additive of claim 4 wherein the cationic water-sol der. This mixture was divided into two equal portions uble aldehyde reactive polymer is a cationic starch. for aging studies. 9. Additive of claim 4 wherein the cationic water-sol One portion was placed into an oven for 30 days of uble aldehyde reactive polymer is a cationic guar gum. aging at 50 C. The others remained at ambient temper 60 10. Additive of claim 7 wherein the polyvinyl alcohol ature on the bench. At the end of the 30 day aging polymer is a completely hydrolyzed grade. period both samples were examined. The oven-aged 11. Additive of claim 4 comprising 25-40% of the sample had darkened slightly from an off-white to a blocked glyoxal resin and cationic water-soluble alde very light beige. The bench sample remained an off hyde reactive polymer, and 60-75% of the polyvinyl white. Both samples were free-flowing powders with 65 alcohol polymer, by dry weight of the additive. no lumps. 12. Additive of claim 11 wherein the reaction product Twenty grams of each sample were placed into sepa is a stable aqueous solution having a solids level of up to rate beakers and slurried in 180 g. of deionized water, 12%. 5,147,908 11 12 13. Additive of claim 4 wherein the reaction has been 18. Additive of claim 17 wherein the dry weight ratio carried out at 85 to 95 C. for 10 to 30 minutes. of blocked glyoxal resin to cationic polymer is within the ratio of 1:4 to 25:1. 14. Additive of claim 13 wherein the aqueous solution 19. Additive of claim 18 wherein the blocking com is fluid having a viscosity of less than 3000 cps when ponent is selected from the group consisting of urea or measured with a Brookfield viscometer with a #3 spin cyclic urea and the level of glyoxal: blocking compo dle at 20 rpm and at room temperature. nent is within the range of about 0.8 to 2:1. 20. Additive of claim 18 wherein the cationic water 15. Additive of claim 14 having a pH of 4-7.5. soluble aldehyde reactive polymer is a cationic acryl 16. A dry free-flowing cationic polyvinyl alcohol 10 amide copolymer. additive for reaction in aqueous solution and use in the 21. Additive of claim 18 wherein the cationic water wet-end of a paper making process comprising: soluble aldehyde reactive polymer is a cationic starch. 22. Additive of claim 18 wherein the cationic water a dry mixture of a blocked glyoxal resin, a cationic soluble aldehyde reactive polymer is a cationic guar water-soluble aldehyde reactive polymer and a 5 gum. polyvinyl alcohol polymer. 23. Additive of claim 20 wherein the polyvinyl alco 17. Additive of claim 16 comprising: hol polymer is a completely hydrolyzed grade. 10 to 60% of the blocked glyoxal resin and the cati 24. Additive of claim 19 comprising 25-40% of the blocked glyoxal resin and cationic water-soluble alde onic water-soluble aldehyde reactive polymer, and 20 hyde reactive polymer, and 60-75% of the polyvinyl 40 to 90% of the polyvinyl alcohol polymer, by dry alcohol polymer, by dry weight of the additive. weight of the additive. is a k

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